Seems like you can extract energy from pretty much anything -- just ask Stanford professor Brian Cantwell. He, along with a team of Stanford researchers, has developed potential rocket fuel from sewage waste.

Essentially, Brian Cantwell et al. have squeezed out nitrous oxide (otherwise known as laughing gas) from sewage waste. According to the researchers, "While nitrous oxide is a powerful greenhouse gas, when it’s burned as rocket fuel, the only byproducts are hot oxygen and nitrogen."

Brian Cantwell's discovery may result in an emissions-free energy source.